1. Field of the Invention
A gel facilitates perforating and non-perforating glaucoma surgery.
2. Description of the Related Art
Glaucoma is a group of eye diseases that gradually steal sight without warning. In the early stages of the disease, there may be no symptoms. Experts estimate that half of the people affected by glaucoma may not know they have it.
There is no cure for glaucoma. However, medication or surgery can slow or prevent further vision loss. The appropriate treatment depends upon the type of glaucoma among other factors.
Primary open angle glaucoma is the most common form of glaucoma. It happens when the eye's drainage canals become clogged over time. The inner eye pressure (also called intraocular pressure or IOP) rises because the correct amount of fluid can't drain out of the eye. With open angle glaucoma, the entrances to the drainage canals are clear and should be working correctly. The clogging problem occurs further inside the drainage canals, similar to a clogged pipe below the drain in a sink. Most people have no symptoms and no early warning signs. If open angle glaucoma is not diagnosed and treated, it can cause a gradual loss of vision. This type of glaucoma develops slowly and sometimes without noticeable sight loss for many years. It usually responds well to medication, especially if caught early and treated.
Angle closure glaucoma is also known as acute glaucoma or narrow angle glaucoma. It is much more rare and is very different from open angle glaucoma in that the eye pressure usually rises very quickly. This happens when the drainage canals get blocked or covered over, like a sink with something covering the drain. With angle closure glaucoma, the iris is not as wide and open as it should be. The outer edge of the iris bunches up over the drainage canals, when the pupil enlarges too much or too quickly. This can happen when entering a dark room.
Treatment of angle closure glaucoma usually involves surgery to remove a small portion of the outer edge of the iris. This helps unblock the drainage canals so that the extra fluid can drain. Symptoms of angle closure glaucoma may include headaches, eye pain, nausea, rainbows around lights at night, and very blurred vision.
Secondary glaucoma can occur as the result of an eye injury, inflammation, tumor or in advanced cases of cataract or diabetes. It can also be caused by certain drugs such as steroids. This form of glaucoma may be mild or severe. The type of treatment will depend on whether it is open angle or angle closure glaucoma.
The success of glaucoma surgery depends on the modification of wound healing. The aim is to limit a healing process and to avoid fibrous tissue formation that are natural biologic responses and are indispensable for all other surgical procedures. Risk factors include age, race, type of glaucoma, conjunctival inflammation and aphakia.
FIG. 1 shows the process of wound healing in glaucoma filtering processes.
As shown in FIG. 1, the stages of wound healing include injury, inflammation, coagulation (clot formation), cellular migration and proliferation, angiogenesis, and scar formation. There are phenomena associated with each stage. For example, inflammation includes vascular permeability, cellular infiltration, plasma proteins, fibrinogen, fibronectin, platelets and cellular procoagulant. Cellular migration and proliferation is associated with fibroblasts, neurophils, macrophages, monocytes and epithelial cells. Scar formation is associated with collagen formation and cross linking.
The strategies to interfere with the process of wound healing after glaucoma surgery include meticulous surgical technique to minimize trauma to the conjunctiva, episclera and iris to decrease leakage of plasma proteins. Other strategies interfere with the process of wound healing at the different stages shown in FIG. 1.
Treatment at the inflammation stage include non-steroidal anti-inflammation drugs (NSAIDs), including aspirin, indomethacin, fluiboprofen. Steroidal drugs used at the inflammation stage can include prednisolon, fluoromethalon and dextramethssone.
Treatment at the coagulation (clot formation) stage can include thrombolytic drugs, urokinase, streptokinase and t-PA. Treatment at the cellular migration stage can include mitomicine C and 5 FU. Treatment at the scar formation stage includes Beta-aminopropionitrile, D-penicillamine and colchicine.
However, there is a continuing need for treatments that will increase the likelihood of a successful outcome from eye surgery, especially glaucoma surgery.